1. Field of the Invention
The present invention relates in general to an oscillator, and more specifically to a digital adjustable chip oscillator.
2. Description of the Related Art
In wireless communication systems, there is a necessity for the phase-lock loop circuit to synchronize with signals from other circuits. In general, the phase-lock loop circuit needs a quartz oscillator serving as an oscillation source. Under development of the integrated circuits technology, it is feasible to lower the cost by integrating external components into a chip and decrease the number of external pins needed. Therefore, there is a necessity to provide a digital adjustable chip oscillator having digital tuning function, self-test systems, and power save modes.